An On-Board Diagnostic, or OBD, system is a computer-based system for diagnosing operational errors. An On-Board Diagnostic, or OBD, system is a computer-based system that was developed by automobile manufacturers to monitor the performance of various components on an automobile's engine, including emission controls. Modern vehicles typically have a vehicle diagnostic system, including one or more separate computer control modules. Examples of such computer control modules (also known as just “modules”) are: a power train control module (PCM), an engine control module (ECM), a transmission control module (TCM), an ABS control module, and an air bag control module. Upon detection of any malfunction, the OBD system provides the owner of the automobile with an early warning (in other words, check engine light in the dashboard of automobile). OBD was primarily introduced to meet EPA emission standards but, through the years, onboard diagnostic systems have become more sophisticated. For example, OBD II, Standard Edition in the mid-90s implemented in light-duty cars and trucks, provides a plurality of sensors to monitor malfunctions with engine, chassis, body, and accessory devices. In a simple scenario, the OBD system detects a malfunction in the engine (or any other component that is monitored by sensors of the OBD system) and signals a warning indicative of such a function. For example, a “check engine” light could be illuminated in an automobile's dashboard indicative of such a malfunction. The automobile's owner, upon noticing such a warning indicator, makes plans for taking the automobile to a repair shop where the malfunction can further be investigated. Upon arrival at the repair shop personnel connect a data link cable that serves as a communications link between the automobile's diagnostic port and an “off-board” device. Off-board devices,” such as scan tools and code readers, are known in the art. Scan tool and code reader testing devices that interface with vehicle diagnostic systems access, display, and/or print vehicle diagnostic information. OBD II (On-Board Diagnostics version II) Scan Tools are one commonly known type of scan tool and are governed by a number of standards, e.g., SAE J1978 Rev. 1998-02 and SAE J1979 Rev. 1997-09. Scan tools are relatively expensive diagnostic devices that have a relatively large number of features and are typically marketed to professional automobile mechanics and service stations. There are different types of scan tools. An “OBD II Scan 45 Tool” complies with the above-identified specifications. By contrast, a “Manufacturer-Specific Scan Tool” is a scan tool that accesses and displays proprietary manufacturer-specific data (and possibly also additionally accesses and displays OBD II data. A code reader is another example of an “off-board” device.
The “off-board” device may be a somewhat stationary scan tool test station, laptop or mobile code reader/scan tool, all connected to a data link cable. An example of a semi-stationary scan tool test station is found in a smog test station where a long data link cable can be seen stretching from the “off-board” device to the automobile.